New Comet
© All Sky Cameras / Peter Jenniskens
This February eta Draconid was filmed by Peter Jenniskens with one of the low-light-level video cameras of the Cameras for Allsky Meteor Surveillance (CAMS) station in Mountain View, California, at 07:59:24 UT on February 4, 2011.

A surprise meteor shower spotted by skywatchers in February was likely caused by cosmic "bread crumbs" left over from an undiscovered comet that could potentially pose a threat to Earth, astronomers announced today (July 27).

The tiny meteoroids that streaked through Earth's atmosphere for a few hours on Feb. 4 represent a previously unknown meteor shower, researchers said. The "shooting stars" arrived from the direction of the star Eta Draconis, so the shower is called the February Eta Draconids, or FEDs for short.

The bits of space rock appear to have been shed by a long-period comet. Long-period comets whiz by the sun only rarely, so it's tough to predict when they last came through our neck of the woods - and when they'll come back, researchers said.

That uncertainty is cause for some concern in this case, they added.

"If the meteoroids can hit us, so can the comet," said FEDs discoverer Peter Jenniskens, of the SETI (Search for Extraterrestrial Intelligence) Institute and NASA's Ames Research Center. "We don't know whether the comet has already passed us by or is still on approach."

Still, Jenniskens stressed that the chances of such a collision are extremely remote.

Scanning the night sky

Jenniskens heads the Cameras for Allsky Meteor Surveillance (CAMS) project, which has been monitoring the San Francisco Bay Area's night skies with low-light video cameras in an effort to map meteor showers.

CAMS cameras picked up the FEDs, bringing the tally of officially recognized meteor showers to 64.

The comet that produced the meteor shower is unknown. It may have last zipped by the sun just a few hundred years ago, or many thousands, researchers said. But it apparently came relatively close to Earth on its last trip through the inner solar system.

At that time, the comet released a cloud of dust, which is now returning. Some dust grains return earlier than others, depending on how elongated their orbit ended up being, and the result is a continuous stream of returning dust grains that we detect only when they barrel into Earth.

"Earth gets hosed typically only once or twice every 60 years by such streams," Jenniskens said.

Learning more about the comet

Jenniskens teamed up with a colleague, Finnish astronomer Esko Lyytinen, to investigate when the FEDs might make another pass. Lyytinen calculated a possible return in 2016 or 2023, and after that not again until 2076, researchers said.

Whenever the FEDs come back, astronomers will study them closely. Future observations of the shower may reveal key information about its parent comet - including whether or not it poses a real danger of ever slamming into Earth.

But Jenniskens urged some perspective, and admonished people not to get into a panic about a potential "doomsday comet."

"Chances are very small that the comet will actually hit us, as such impacts are rare in Earth's history," he said.